1. Field of the Invention
The present invention relates to a wrench and, particularly, to a wrench with a driving end which is open-ended. An object can be turned quickly with the open-end wrench. The open-end wrench is turned in one direction to turn the object and in another direction to turn relatively to the object.
2. Description of the Related Art
TW Pats. No. M384740 and M392040 show a wrench including a driving end which is open-ended. An object can be turned quickly with these wrenches, because when they are turned in one direction to turn the object, they are adapted to turn in another direction to move relatively to the object to a position that allows a better turning position for the user, which was done conventionally by disengaging the wrench with the object and then reengaging it.
TW Pat. No. M384740 shows its driving end including two jaws and a space defined between the jaws. An object is disposed in the space and clamped by the jaws when in engagement with the wrench. The driving end further includes a movable engaging member pivotally fixed and disposed in a recess defined in each jaw. The movable engaging member is fixedly engaged with the object when the wrench is turned in one direction with the object and is urged to move pivotally by the object when the wrench is turned in another direction to turn relatively to the object. Further, a spring is used to bias one movable engaging member. Furthermore, the movable engaging member engages with the object by an engaging end abutting against the object and is pivotally attached in the recess by attaching a connecting end to a bottom wall of the recess. The connecting end and the engaging end are formed as one piece. Therefore, the connecting end is not fixed as the movable engaging member is pivoted. Moreover, each movable engaging member is not supported by a lateral wall of the recess. While the movable engaging member is adapted to be pivoted without moving against the lateral wall of the recess and since friction does not exist between the movable engaging member and the recess, a large stress concentration exists on the connecting end of the movable engaging member.
TW Pat. No. M392040 shows its driving end with two jaws, with one of the jaws including a movable engaging member and a fixed member disposed in a recess defined in the jaw. The movable engaging member is biased by a spring that is supported by the fixed member and that is activated by the object engaged with the wrench. Furthermore, the movable engaging member is restrainedly moved in the recess by an axle that inserts therethrough and is fixed to the jaw. Therefore, the axle prevents the movable engaging member from disengagement from the recess.
It is still desirable to design an open-end wrench for quickly turning an object that includes a simple structure and has fewer parts than the conventional wrenches of this kind without compromising the use life of the parts. The parts are extended in life by increasing surface contacts and reducing stress concentrations therebetween.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.